mm: workingset: prevent lruvec release in workingset_refault()

In the near future, a folio will no longer pin its corresponding memory
cgroup.  So an lruvec returned by folio_lruvec() could be released without
the rcu read lock or a reference to its memory cgroup.

In the current patch, the rcu read lock is employed to safeguard against
the release of the lruvec in workingset_refault().

This serves as a preparatory measure for the reparenting of the LRU pages.

Link: https://lore.kernel.org/e3a8c19a9b18422b43213f6c89c451c5b6ca1577.1772711148.git.zhengqi.arch@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Allen Pais <apais@linux.microsoft.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Yosry Ahmed <yosry@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/workingset.c b/mm/workingset.c
index 6971aa163e466e1bc899fab85779e1e8206ecdb5..2de2a355f0f86f6b67b6c2870fb20ab22c9ccfaf 100644 (file)
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -546,6 +546,7 @@ bool workingset_test_recent(void *shadow, bool file, bool *workingset,
 void workingset_refault(struct folio *folio, void *shadow)
 {
        bool file = folio_is_file_lru(folio);
+       struct mem_cgroup *memcg;
        struct lruvec *lruvec;
        bool workingset;
        long nr;
@@ -567,11 +568,12 @@ void workingset_refault(struct folio *folio, void *shadow)
         * locked to guarantee folio_memcg() stability throughout.
         */
        nr = folio_nr_pages(folio);
-       lruvec = folio_lruvec(folio);
+       memcg = get_mem_cgroup_from_folio(folio);
+       lruvec = mem_cgroup_lruvec(memcg, folio_pgdat(folio));
        mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr);
 
        if (!workingset_test_recent(shadow, file, &workingset, true))
-               return;
+               goto out;
 
        folio_set_active(folio);
        workingset_age_nonresident(lruvec, nr);
@@ -587,6 +589,8 @@ void workingset_refault(struct folio *folio, void *shadow)
                lru_note_cost_refault(folio);
                mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + file, nr);
        }
+out:
+       mem_cgroup_put(memcg);
 }
 
 /**